Speaker systems in which multiple speaker units are arranged in a speaker housing include one called an array speaker apparatus, which is sometimes used as a broadcast facility. As the array speaker apparatus, there is one that can control directivity of a sound wave by providing a delay circuit for each of speaker units and on a sound signal supplied to the speaker units, adjusting a delay time for each of the speaker units (e.g., Patent Literature 1).
The respective speaker units of the above-described array speaker apparatus emit the same sound waves while producing slight time differences, and therefore even in the case where some of the speaker units are in failure, the failure cannot be easily realized. For example, even in the case where some of the speaker units are in failure, and thereby abnormality occurs in the directivity of the array speaker apparatus, the abnormality cannot be found unless an observation is made at a listening point where abnormal sound pressure occurs. Also, even in the case where the failure is realized from a reduction in sound level, or the like, it is not easy to specify which of the speaker units is in failure.
Meanwhile, as an array speaker apparatus incorporating a power amplifier that amplifies a sound signal to supply the amplified signal to a speaker unit, there is known one that can detect overcurrent or overvoltage occurring in an amplifier circuit, or a temperature rise of a circuit element. However, such failure detection utilizing a detecting function of the power amplifier itself has a problem of being unable to detect miswiring to the speaker unit or trouble of the speaker unit itself.
For example, in the case of an array speaker apparatus that adjusts a delay of a sound signal with a DSP (Digital Signal Processor), the DSP adjusts a delay time for each of channels corresponding to unit attachment positions on a speaker housing. For this reason, respective speaker units should be connected to the channels corresponding to the positions on the speaker housing; however, failure detection utilizing a power amplifier cannot detect misconnection between the DSP and a speaker unit. Also, in the case where a speaker unit is a unit using cone paper as a diaphragm, failure detection utilizing a power amplifier cannot detect a tear of the cone paper.